Officials are struggling to clean up the grey skies of its major cities, as pollution takes a rising toll on health and growth, while supporting an industry key to its booming growth.

The country's car fleet has been growing, with an estimated 1,000 new private vehicles hitting the streets of Beijing alone each day, the report said.

But for those members of the growing middle class who have been car owners too long to face being crammed into a bus or train, taxis will still be allowed to ply the otherwise car-free streets.